Setting: Pulmonary department of a medical academy in Ankara, Turkey.
Objective: Neopterin is a marker of cell-mediated immunity, and it has been demonstrated that neopterin levels of various body fluids could be elevated in tuberculosis. We aimed to investigate diagnostic values of serum, pleural fluid and urine neopterin measurements in tuberculous pleurisy (TP).
Design: Serum, pleural fluid and urine neopterin levels were measured in 34 patients with TP and in 29 patients with pleural effusion of non-tuberculous origin as controls.
Results: Neopterin levels in serum, pleural fluid and urine (38.28 +/- 14.18 nmol/l, 38.97 +/- 14.18 nmol/l and 759.15 +/- 622.74 micromol/mol, respectively) were significantly higher in patients with TP than those with non-tuberculous pleural effusion (22.57 +/- 6.02 nmol/l, 21.88 +/- 6.90 nmol/l and 343.10 +/- 233.65 micromol/mol, respectively). Pleural fluid neopterin > or =30 mol/l gave the best diagnostic yield, with 85% sensitivity, 93% specificity, 94% positive predictive value, 84% negative predictive value and 89% diagnostic accuracy, although it is not superior to pleural fluid adenosine deaminase determination.
Conclusion: We have suggested that elevated serum, pleural fluid and urinary neopterin levels in TP with respect to pleural effusions of non-tuberculous origin may reflect activation of cell-mediated immunity and that pleural fluid neopterin measurement may be of value in the differential diagnosis of TP.